Preheat oven to 325°F. Grease and flour a bundt pan.
Sift together baking soda, baking powder, flour and salt. Set aside.
In a large bowl cream the 3/4 cup of butter and sugar. Mix in the egg, apple butter, and vanilla.
Add in half of the dry ingredients and then the buttermilk. Add in the remaining dry ingredients and mix until the ingredients just come together. Do not over mix.
Pour the batter into the prepared bundt pan. Spread into an even layer.
Bake for 60-75 minutes or until a toothpick can be inserted and removed clean.
Remove the pan from the oven and let the cake cool 10-15 minutes. Then invert the cake onto a cooling rack.
For the Glaze: Heat and stir the 1/4 cup of butter in a pan over medium heat until just golden brown. (Watch carefully as the butter will burn quickly.)
Transfer brown butter to a small bowl and add the powdered sugar. Add the hot water one teaspoon at a time. Whisk with a fork until smooth and the glaze is a thick drizzling consistancy.
Immediately drizzle the glaze over the cake.